Question

8а в квадрате -8ab-5a + 5b, якщо а = 1 дробь 8, б = -3 дробь 4;

Answer 1

$8a^2-8ab-5a+5b=a(8a-5)-b(8a-5)=(a-b)(8a-5)$

якщо $a= \frac{1}{8}; b=- \frac{3}{4}$

$(a-b)(8a-5)=( \frac{1}{8}-(- \frac{3}{4} ) )(8* \frac{1}{8}-5)=( \frac{1}{8}+ \frac{6}{8} )(1-5)= \\ = \frac{7}{8}*(-4)=- \frac{7}{2}=-3.5$

Answer 2

$8a^2-8ab-5a+5b=8a(a-b)-5(a-b)=(a-b)(8a-5);\\(\frac{1}{8}-(-\frac{3}{4}))(8*\frac{1}{8}-5)=-4(\frac{1}{8}+\frac{3}{4})=-4*\frac{1+6}{8}=-\frac{7}{2}=-3,5$